Dynamic ear phone



Jan. 18, 1966 .1.. KLIEWER 3,230,319

DYNAMIC EAR PHONE Filed May 24, 1965 F/G/ 44 43 42 4/ 47 46 m4 /7 /9 /&

INVENTOR. DONALD L EROV KL lEWER AWORNE) United States Patent 3,230,319DYNAMIC EAR PHONE Donald Leroy Kliewer, East Providence, R.I., assignorto Plastic Mold 8; Engineering Co., Providence, R.I., a corporation ofRhode Island Filed May 24, 1963, Ser. No. 282,998 3 Claims. (Cl.179115.5)

This invention rel-ates to dynamic ear phones and more particularly to adiaphragm which is provided with a rigid medial auxiliary batten.

One object of the present invention is to eliminate the vibrations ofthe diaphragm which interfere with the tonal qualities of the diaphragm.

And still another object of the present invention is to have the outercircumferential area of the diaphragm produce low frequency sound waveswhile the stiffened medial area of the diaphragm produces high frequencysound waves.

In the past the surface of the diaphragm reacted with a wave producingmotion so that more than one sound was produced. The secondary or excesssound waves are undesirable because they produce sound waves whichinterfere with the primary sound wave and thereby interfere with thetonal quality of the primary sound wave.

The present invention overcomes this undesirable condition through astructure which provides a stiff auxiliary membrane attached to themedial area of the diaphragm with entrapped air between the stiffauxiliary membrane and diaphragm.

The prior art discloses a stiff auxiliary membrane inserted into amedial area orifice in the diaphragm. The present constructionencompasses a stiff membrane attached in the medial area of thediaphragm and united by means of the peripheral area of the stiffmembrane. There is entrapped air between the membrane and diaphragm. Thepresent invention contemplates a primary and a secondary medialdiaphragm construction and not a single thick medial diaphragm.

Other objects of the present invention will be pointed out in part andbecome apparent in part in the following specification and claims.

Referring to the drawings in which similar characters of referenceindicate corresponding parts in all the figures:

FIGURE 1 is a vertical medial sectional view through the new andimproved dynamic ear phone.

FIGURE 2 is a view similar to FIGURE 1, taken in a vertical plane atright angles to the vertical plane of FIGURE 1.

FIGURE 3 is an exploded perspective view of the construction illustratedin FIGURES l and 2.

FIGURE 4 is a perspective view of a detail in construction of the voicecoil attached to the diaphragm.

In proceeding with this invention there is provided a circular frame,generally indicated by reference numeral 11, comprising an outwardlyextending circular flange 12, a circular shell 13, and a tapered bodysection 14 provided with a circular band 15 and a plurality of air ports16.

Circular flange 12 is provided with a chamber 17 having a stepped wallwhich provides a guard seat 18, a diaphragm seat 19 and a sloped side 20terminating at the axial bore 21 of shell 13.

A magnetic structure having inner and outer pole pieces is required. Onesuch structure will be described. Any equivalent structure may besubstituted.

A hollow cylindrical member, serving the function of a pole piece, isgenerally indicated by reference numeral 23 and comprises a cylindricalwall 24 having a bottom plate 25 and a top plate 26 provided with acentral opening 27. The hollow area of cylindrical member 23 isindicated by reference numeral 28. Top plate 26 provides the outer polepiece for the magnetic structure and may have a circular recess 38.

Hollow cylindrical member or pole piece 23 is fastened in circular shell13 by mean-s of a tight fit in axial bore 21.

A solid cylindrical magnet 30 is centrally disposed within hollowcylindrical member 23 and is fastened to bottom plate 25 by means of anelectrically insulating cement 32. Bottom plate 25 may be provided witha circular recess 31 for the purpose of holding the insulating cement 32and to permit the cylindrical magnet 30 to be embedded therein. Magnet30 projects through central opening 27 with an air gap 33 betweencylindrical magnet 30 and the side of central opening 27. The magnet 30may be termed the inner pole piece.

A diaphragm, generally indicated by reference numeral 40 is preferablyfabricated from a membrane of polyethylene terephthalate or a co-polymerof polyvinylidine chloride. One aspect of the former is knowncommercially as Mylar and the latter as Saran-Wrap.

Diaphragm 40 is of a shape illustrated in the drawing and consists of ageneral conical shape having a raised central portion or medial dome 41and a tapering outwardly extending circular side portion 42 having a circular crimped area 43 which terminates in a flat rim 44. A plastic,dome-shaped stiff auxiliary membrane 45 having a circular band 46 isplaced over medial dome 41 with the circular band 46 fastened to saidcircular side portion 42 by means of a heat seal or an adhesive. An airpocket 47 is formed between dome 41 and stiff auxiliary membrane 45.Flat rim 44 is secured to diaphragm seat 19 by means of an adhesive.

The tapering outwardly extending circular side portion 42 is the area ofthe diaphragm which produces the low frequency sound waves. The plastic,dome-shaped stiff auxiliary membrane 45 in cooperation with medial dome41 produce the high frequency sound waves.

A voice coil 35 having terminal ends 36, 37 is fastened to diaphragm 40by means of an adhesive 39. Medial dome 41 assists in locating theconvolutions of the voice coil in exact medial position on the diaphragm40. The exact locating of the voice coil on the diaphragm is necessaryfor the proper location of the voice coil in air gap 33 and the properfunctioning of the voice coil and diaphragm.

Voice coil 35 is placed in central opening 27 surrounding cylindricalmagnet 30 and within air gap 33.

A guard plate, generally indicated by reference numeral 50, is providedwith a plurality of perforations or air spaces 51. Guard plate ispreferably fabricated from metal such as aluminum and is fastened toguard seat 18 by means of a press fit.

The structure described supra provides a new and improved dynamic earphone having superior tonal qualities. However, it has been found thatthe additional structure about to be described further adds to the tonalqualities of the ear phone.

A cover, generally indicated by reference numeral 52, comprises a base53, and an integrally formed circular side wall 62 provided with aperipheral edge 63 which is fastened to circular band 15. A cavity 54 isformed between cover 52 and circular frame 11.

Silk in the form of disks 60 or any other air porous material isfastened by means of an adhesive over the ends of air ports 16 and totapered body section 14 on cavity 54 side of air ports 16. Porousmaterial disks 60 filter the air which passes from chamber 17 to cavity54 through air ports 16. Cavity 54 is provided for back loading as willhereinafter appear.

Diaphragm 40 divide chamber 17 into two sections. Inner or rear section17 and outer or front section 17A.

Lead wires 36A, 37A are provided as extensions to terminal ends 36, 37respectively. Body section 14 is provided with two channels 70, 71.Cover 52 is provided with an opening 73. Lead wires 36A, 37A are passedthrough opening 73 and channels 70, 71 respectively and are united, asby twisting, to ends 36, 37 respectively.

In operation, lead wires 36A, 37A are attached to a sound source (notshown) which provides the electrical energy to vibrate the voice coiland diaphragm.

A DC. magnetic field exists between magnet and top plate 26 acrosscentral opening 27. The vibration of the voice coil in the DC. magneticfield creates a vibration frequency in the diaphragm 40. The shape ofpole piece 23 provides a path for the harnessing of the magnetic linesof force inherent in magnet 30.

Opening 73 is just large enough to accommodate lead wires 36A, 37A.Chamber 54 is filled with atmospheric pressure air. As diaphragm 40vibrates it moves air in front section 17A through air spaces 51 toproduce sound waves. Diaphragm 40 also moves the air in rear section 17through ports 16 into air filled chamber 54. Porous disks 60 provide aresistance to the movement of air through ports 16. Chamber 54 providesback pressure to the movement of air from ports 16 into chamber 54.

In this manner, the air in rear section 17 impedes the vibration ofdiaphragm 40 and thereby the frequency response and tonal quality ofdiaphragm 40.

Plastic dome-shaped stiff auxiliary membrane stiifens diaphragm 40 inthe medial area whereby the frequency response of the medial area isalso impeded.

It is the control of the frequency response of the medial area of thediaphragm 40 through stiff auxiliary membrane 45 and the control of thefrequency response of the entire diaphragm 40 through the impedance ofair in rear section 17 which provides the present structure with theability to produce both low and high frequency responses and primarysound waves unfettered with secondary sound waves. Secondary sound wavesare produced by the uncontrolled vibrations of a diaphragm.

Applicant has produced a diaphragm which is both a tweeter and a woofer.

Having shown and described a preferred embodiment of the presentinvention by Way of example, it should be realized that structuralchanges could be made and other examples given Without departing fromeither the spirit or scope of this invention.

What I claim is:

1. A dynamic ear phone comprising a frame having a shell provided withan axial bore, a tapered body section provided with a plurality of airports, and a chamber having a wall provided with a diaphragm seat, amovable diaphragm of a general conical shape having a medial area and atapering outwardly extending circular side portion, stiff auxiliarymembrane, means fastening said stiif auxiliary membrane to saiddiaphragm at said medial area with an air space between said medial areaand said stiff auxiliary membrane, a voice coil, means fastening saidvoice coil to said diaphragm at said medial area, a magnetic structurehaving inner and outer pole pieces provided with an air gaptherebetween, means fastening said movable diaphragm in said diaphragmseat with said voice coil disposed within said air gap, said diaphragmbeing located in said chamber and dividing said chamber into twosections, means fastening said magnetic structure in said axial bore, acover provided with a cavity, and means fastening said cover to saidframe to provide back pressure on said diaphragm through one of said twosections, said plurality of air ports and said cavity.

2. A dynamic ear phone comprising a frame having a shell provided withan axial bore, a tapered body section provided with a plurality of airports, and a chamber having a wall provided with a diaphragm seat, amovable diaphragm fabricated from a membrane of polyethyleneterephthalate or a membrane of a co-polymer polyvinylidine chloride, andhaving a generally conical shape provided with a medial area and atapering outwardly extending circular side portion having a circularcrimped area and a flat rim, a dome-shaped stiff auxiliary membranefabricated from plastic material, means fastening said dome-shaped stilfauxiliary membrane to said diaphragm at said medial area with an airspace between said medial area and said dome-shaped stiff auxiliarymembrane, a voice coil having terminal ends adapted to extend beyondsaid frame, means fastening said voice coil to said diaphragm at saidmedial area, a magnetic structure having inner and outer pole piecesprovided with an air gap therebetween, means fastening said movablediaphragm through said flat rim in said diaphragm seat with said voicecoil disposed within said air gap, said diaphragm being located in saidchamber, thereby dividing said chamber into a front section and a rearsection, means fastening said magnetic structure in said axial bore, acover provided with a cavity, and means fastening said cover to saidframe to provide back pressure on said diaphragm through said rearsection, said plurality of air ports and said cavity.

3. A dynamic ear phone consisting of a circular frame having a circularshell provided with an axial bore, a tapered body section provided witha circular band and a plurality of air ports, and a chamber having astepped wall providing a guard seat, a diaphragm seat and a sloping sideterminating at said axial bore, a hollow cylindrical member pole piececomprising a cylindrical wall having a bottom plate and a top plateprovided with a central opening, means fastening said hollow cylindricalmember pole piece in said axial bore, a cylindrical magnet, electricallyinsulating means fastening said cylindrical magnet to said bottom platewith one end of said cylindrical magnet located in said central opening,a diaphragm comprising a general conical shape having a medial dome, atapering outwardly extending circular side portion provided with acircular crimped area and a flat rim, a dome-shaped stiff auxiliarymembrane means fastening said dome-shaped stiff auxiliary membrane oversaid medial dome and to said tapering outwardly extending circular sideportion, means fastening said flat rim to said diaphragm seat, an airpocket located between said medial dome and said stiff auxiliarymembrane, a voice coil provided with terminal ends, means fastening saidvoice coil to said diaphragm, said voice coil being located in saidcentral opening and around said cylindrical magnet, a guard plateprovided with a plurality of air pockets, means fastening said guardplate in said guard seat, a plurality of air porous disks, meansfastening said plurality of air porous disks over said plurality of airports,

- a cover provided with a base and a circular side wall hav- ReferencesCited by the Examiner UNITED STATES PATENTS 6/1953 Levy et al 181-326/1958 Olson et al. l7 9l ROBERT H. ROSE, Primary Examiner.

1. A DYNAMIC EAR PHONE COMPRISING A FRAME HAVING A SHELL PROVIDED WITHAN AXIAL BORE, A TAPERED BODY SECTION PROVIDED WITH A PLURALITY OF AIRPORTS, AND A CHAMBER HAVING A WALL PROVIDED WITH A DIAPHRAGM SEAT, AMOVABLE DIAPHRAGM OF A GENERAL CONICAL SHAPE HAVING A MEDIALDE AREA ANDA TAPERING OUTWARDLY EXTENDING CIRCULAR SIDE PORTION, STIFF AUXILIARYMEMBRANE, MEANS FASTENING SAID STIFF AUXILIARY MEMBRANE TO SAIDDIAPHRAGM AT SAID MEDIAL AREA WITH AN AIR SPACE BETWEEN SAID MEDIAL AREAAND SAID STIFF AUXILIARY MEMBRANE, A VOICE COIL, MEANS FASTENING SAIDVOICE COIL TO SAID DIAPHRAGM AT SAID MEDIAL AREA, A MAGNETIC STRUCTUREHAVING INNER AND OUTER POLE PIECES PROVIDED WITH AN AIR GAPTHEREBETWEEN, MEANS FASTENING SAID MOVABLE DIAPHRAGM IN SAID DIAPHRAGMSEAT WITH SAID VOICE COIL DISPOSED WITHIN SAID AIR GAP, SAID DIAPHRAGMBEING LOCATED IN SAID CHAMBER AND DIVIDING SAID CHAMBER INTO TWOSECTIONS, MEANS FASTENING SAID MAGNETIC STRUCTURE IN SAID AXIAL BORE, ACOVER PROVIDED WITH A CAVITY, AND MEANS FASTENING SAID COVER TO SAIDFRAME TO PROVIDE BACK PRESSURE ON SAID DIAPHRAGM THROUGH ONE OF SAID TWOSECTIONS, SAID PLURALITY OF AIR PORTS AND SAID CAVITY.